While an unplanned dalliance in the woods will often lead to an unwanted litter, organised matings can require a lot of planning. Everything must be perfectly aligned for a natural mating to happen and result in a litter. Mother nature usually expertly takes care of this. When matings are planned however, us humans take control of the variables, and things can go awry!

If you take your bitch to a stud dog to be bred, you will be paying for the privilege and expect several puppy shaped results. That’s a lot of pressure! It obviously takes two to tango, and there can be problems with the bitch that mean she can’t conceive, but here we will explore infertility in male dogs. What are the causes, how can it be diagnosed, and what can be done about it? 

Husbandry problems:

The most likely reason a mating fails to produce a litter is that of husbandry (i.e. timing or behaviour). Medical and functional problems can also cause infertility, but these are much rarer.

Timing

Female dogs cycle like humans do, but only about twice a year. Within each cycle, there is a very short window when she ovulates, and she must be mated during this time to become pregnant. As a general rule, ovulation occurs about 12 days after the start of her oestrus cycle, but there is some variation here. Two or three matings are often done, two to three days apart around this time frame to increase the chances of ‘catching’ the right window. 

The owner of the bitch can take measures to try to identify the exact timing of ovulation, by getting vaginal swabs done by their vet. These can be checked under a microscope and will show the precise cellular changes that are occurring in real time, so a mating can be organised. This will also tell you when it is too late, and any further matings will not be successful. Blood tests can also show the hormonal changes during the oestrus cycle and identify the best time for mating, but the cost and practicalities of this often render them useless in reality. They are expensive and need to be sent to a laboratory for analysis, so by the time the vet has the blood result, it’s too late. 

Behaviour and diagnosing infertility in male dogs

Libido (sex drive) is a very individual thing. Some owners get their dogs castrated after they have worked their way through every household cushion available, and Nana’s leg becomes the final straw. Others can remain ‘entire’ their whole life and never show much interest. If you are destined to become a stud dog, you need to find that happy medium! 

Some male dogs just don’t have a great libido, plain and simple. If they don’t want to do the job, then they won’t do it! Career change needed. The females also need to be in the right frame of mind. Their hormonal changes have a big part to play; if she doesn’t ‘stand’ for a male dog (i.e. allow mating to occur), then it is likely she is not at the right stage of her oestrus cycle for conception. 

Some dogs (both male and female) are inherently aggressive or anxious, and mating just may not be something they are happy to partake in. If a stud dog is otherwise fertile, but his libido or behaviour is letting the side down, his sperm can be collected and used for artificial insemination (AI). This is not simple though, and his genes would need to be exceptionally desirable to warrant the effort. 

The dog’s physical health can also have an effect on mating. The male has to be able to mount the female for mating to occur, so if they have any pain in their body they may be unable (or unwilling) to mount the female. Similarly, if the bitch has any points of pain, she may not allow the stud to mount her. The pain could be anything from joint or back pain, (perhaps from an injury or arthritis) to an ear infection or wound; anything that makes them more sensitive to being touched. 

Medical problems in infertile male dogs:

Benign Prostatic Hyperplasia

Benign Prostatic Hyperplasia (BPH) is a common condition in older entire male dogs. Their testosterone drive causes the prostate gland to become enlarged, which can lead to compression of the urethra or colon and cause difficulty in passing urine or faeces as a result. Blood can also often be seen in the urine or dripping from the penis, and will also be present in any ejaculate. BPH doesn’t actually affect fertility, but it can lead to a more serious condition called prostatitis which does, so it should be treated. The blood in the ejaculate will also make freezing semen for AI unsuccessful, so this may need to be considered in a breeding stud dog. 

The good news is that treatment for BPH is possible. The bad news is that surgical castration is generally the best treatment option, which will unfortunately scupper any plans for future breeding. Medical treatment options do exist for dogs intended for breeding or showing, where surgical castration is undesirable. Some of the drug options have no effect on libido or sperm quality, but others will wipe out both, so a detailed discussion with your vet should be had before decisions are made. Serious consideration should be given to what is best for the dog himself, not just his chance of future breeding. 

Prostatitis

A dog with BPH can go on to develop a bacterial infection of the prostate gland, called prostatitis, which reduces the sperm quality and fertility. Prostatitis can vary in severity from mild recurrent urinary tract infections, to severe pain, a high temperature, and possibly even septicaemia. The treatment required will depend on the severity of the infection, but will typically include antibiotics, iv fluids, pain relief and anti-inflammatories. Antibiotic treatment can be needed for a month or more, and treatment for BPH is also required for success. 

Increased scrotal temperature 

Testicles are delicate things, so it is a wonder that they are so exposed! There is actually a very good reason for this; sperm are produced in the testicles, and this process is very sensitive to high temperatures. Having them sitting outside the body means the testicles are kept at a lower temperature than the core body, and sperm production can be optimal. Anything that causes the temperature of the testicles to rise can reduce sperm production and fertility for more than 60 days after the initial illness. If severe or prolonged, fertility can even be permanently affected. There can be several reasons testicles may become too warm:

  • High environmental temperatures e.g. suffering from heatstroke. 
  • Inflammation of the scrotum (e.g. a dermatitis / skin infection) – inflammation of the skin makes it warm, and the temperature inside the testicles will therefore increase too. 
  • Fever – if the temperature of the whole body is raised, the temperature of the testicles will be too. So a fever for ANY reason can reduce fertility.
  • Trauma – if the dog gets injured in this area, maybe from a dog bite or a barbed wire wound, the testicles can become swollen and hot.  

Tumours 

Testicular tumours:

As with humans, tumours can either be benign (don’t spread to other parts of the body), or malignant (invasive and can spread). Both types of tumours can affect fertility because of the physical damage to the normal tissue. Testicular tumours can also be ‘functional’, producing the hormone oestrogen which can cause male infertility. If the tumour is just in one testicle, in theory that testicle can be removed to leave only the healthy, fertile one, but in reality a full castration is more often advised which of course will leave the dog infertile. A small price to pay if it offers a chance to cure a malignant cancer though.  

Prostate tumours:

Tumours of the prostate gland in dogs are, unfortunately, usually malignant. They are typically aggressive, with most having spread already before they are diagnosed, and there is no effective cure. Radical surgery and radiotherapy come with high risk of side-effects (such as lasting urinary incontinence) which are hard to manage, so most dogs are given anti-inflammatories and pain relief until euthanasia is sadly required. They will of course affect fertility, but this becomes an insignificant side-effect once the diagnosis is made.

Systemic Infection 

Brucellosis is a rare bacterial infection in dogs, but importantly can infect humans too. Public awareness of Brucella has risen in the UK in recent years, as the infection has been bought over by imported dogs. Young children, immunocompromised people and pregnant women are most vulnerable to it, where it can cause miscarriages and stillbirths. In dogs, the signs can be varied with reproductive problems amongst others, causing abortion, weak puppies, and infertility in both male and female dogs. There is no way to completely cure it, so if a dog is diagnosed with brucellosis, euthanasia is generally recommended to prevent potential spread to humans or other dogs. 

Functional Problems:

A full evaluation of the dog’s reproductive health and a semen evaluation can determine whether there is an inherent problem with the stud dog’s reproductive organs or the sperm itself. This will include an evaluation of the prostate and general health as discussed above. 

Reproductive Examination

The penis and prepuce should be checked for any abnormalities that might prevent mating (e.g. growths, swellings, sores, anatomical abnormalities). The presence of phimosis (an inability to extrude the penis through a small preputial opening) will naturally affect mating, and can be easily assessed with a physical examination. 

The scrotum and testicles should be checked for size, symmetry, lumps, infections etc that may be significant.

A semen evaluation can also be done

Not a job for an amateur perhaps, but with a sterile artificial vagina, the presence of a bitch in season, and a good amount of compliance, it is possible! The sperm can then be viewed under a microscope to check their appearance, shape, mobility, and number. Any abnormalities here are likely to be significant, and equally a normal sperm evaluation should point you towards another cause of infertility. Recent illness and fever can temporarily impact sperm quality, so this should also be taken into account. If any unusual cells such as red blood cells or white blood cells are seen in the ejaculate, this warrants further investigation of a possible underlying medical cause. 

An ultrasound of the testicles can also be done, which will check for any masses / abnormalities that are not visible from the outside. If found, these abnormalities can even be biopsied to find out exactly what they are. 

Conclusion

So, there’s a lot more to infertility in male dogs than you may have previously realised! It can be a real problem for breeders so having an idea of the causes and how these problems can be managed will help achieve the end goal – a litter of perfect puppies.